PU-Foam-Flexible OPEN
Grade
OPEN = open-cell breathable soft foam
Pick when air permeability / squeeze-recovery of a real seat or sponge must be simulated; absorbs water and soils easily.
Values for the OPEN condition
Other PU-Foam-Flexible grades and fills
PU-Foam-Flexible is listed in 7 conditions; see the grade overview at PU-Foam-Flexible.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
OPENThis page Open-cell breathable soft foam | Pick when air permeability / squeeze-recovery of a real seat or sponge must be simulated; absorbs water and soils easily. | — | 0.25 | 200 | 12 Shore A |
Low-density soft foam, 0.15–0.22 g/cm³ | Pick for very soft seat/cushion feel and lightest parts; low tear strength, fragile thin walls. | — | 0.4 | 180 | 20 Shore A |
Flame-retardant flexible foam | Pick for automotive interior, rail or transit mock-ups that must pass burn-rate testing; slightly stiffer and darker. | — | 0.8 | 120 | 45 Shore A |
STD-D350Default Standard flexible foam, ~0.35 g/cm³ molded density | Default cushioning/comfort prototype foam — balanced softness, tear strength and demold time. | — | 0.9 | 150 | 40 Shore A |
Aliphatic / UV-stabilized light-stable flexible foam | Pick for white or light-coloured show models that must not yellow under lighting or sunlight; noticeably more expensive. | — | 0.9 | 150 | 40 Shore A |
High-density semi-firm foam, 0.50–0.70 g/cm³ | Pick when the foam part must carry load, hold threads/inserts or survive handling; heavier and firmer. | — | 2 | 110 | 62 Shore A |
Self-skinning / integral-skin flexible foam | Pick for grips, armrests and steering-wheel style parts needing a dense paint-ready skin over a soft core. | — | 2 | 130 | 15 Shore D |
What is PU-Foam-Flexible OPEN?
PU-Foam-Flexible OPEN is PU-Foam-Flexible in the OPEN grade — pick when air permeability / squeeze-recovery of a real seat or sponge must be simulated; absorbs water and soils easily. PU-Foam-Flexible OPEN has a tensile strength of 0.25 MPa (0.0363 ksi), weaker than 100% of polyurethane grades. Elongation at break is 200% and the elastic modulus is 0 GPa (1.74×10⁻⁴ Msi). PU-Foam-Flexible OPEN has a density of 0.12 g/cm³ (0.0043 lb/in³), lighter than 100% of polyurethane grades. Its glass-transition temperature is -45°C (-49 °F). STD-D350 is the default condition FabDigit quotes; OPEN is available on request or by drawing note.
Advantages
- Forms and bends easily — 95/100, better than 106% of polyurethane grades
- Lightweight — 0.12 g/cm³ (0.0043 lb/in³), better than 100% of polyurethane grades
- Ductile — tolerates forming and impact — 200%, better than 86% of polyurethane grades
Limitations
- High mold shrinkage — 1.5%, worse than 106% of polyurethane grades
- Absorbs moisture — dry before molding — 60%, worse than 105% of polyurethane grades
- Low stiffness — 0 GPa (1.74×10⁻⁴ Msi), worse than 100% of polyurethane grades
- Poor heat conductor — 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 100% of polyurethane grades
- Difficult to machine — 20/100, worse than 95% of polyurethane grades
PU-Foam-Flexible OPEN properties
Typical room-temperature values for PU-Foam-Flexible OPEN; 19 are specific to this condition. Other listed values are PU-Foam-Flexible reference data and may not represent this condition. Bars are the position among polyurethane grades.
Physical4
PU-Foam-Flexible OPEN has a density of 0.12 g/cm³ (0.0043 lb/in³), lighter than 100% of polyurethane grades. Its glass-transition temperature is -45°C (-49 °F).
Mechanical10
PU-Foam-Flexible OPEN has a tensile strength of 0.25 MPa (0.0363 ksi), weaker than 100% of polyurethane grades. Elongation at break is 200% and the elastic modulus is 0 GPa (1.74×10⁻⁴ Msi).
Thermal8
PU-Foam-Flexible OPEN is rated for continuous service to 70°C (158 °F). It conducts heat at 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 100% of polyurethane grades. Thermal expansion is 90 µm/m·K (50 µin/in·°F).
Electrical3
PU-Foam-Flexible OPEN has an electrical resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 74% of polyurethane grades. UV resistance is poor.
Sustainability4
Producing a kilogram of PU-Foam-Flexible OPEN takes about 103 MJ of energy and emits 4.6 kg of CO₂ — less than 62% of polyurethane grades. Typical recycled content is 0%.
Manufacturability5
PU-Foam-Flexible OPEN's machinability is poor (20/100, worse than 95% of polyurethane grades); weldability not recommended (0/100); formability excellent (95/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PU-Foam-Flexible OPEN
Is PU-Foam-Flexible easy to machine?
Trim with sharp blades, hot wire or band knife; milling smears and tears — use very sharp single-flute tools, high rpm, low feed and vacuum support.
Can PU-Foam-Flexible be welded?
Not weldable; join with PU or contact adhesive, or overpour a second shot against the cured foam skin.
Can PU-Foam-Flexible be formed, bent or molded?
Degas A/B, mix by weight, pour into a silicone vacuum-casting mould with vents and 15–30 % overpack; cream time ~30–60 s, demold 20–60 min, full properties after 24 h (post-cure 60–70 °C accelerates).
What surface finishes work on PU-Foam-Flexible?
Integral-skin surfaces take flexible PU primer/paint or flock; open-cell foam must be skinned or sealed before painting; sand only with the surface chilled or with abrasive mesh.
PU-Foam-Flexible chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| polyether polyol (polyol component A)triol/diol blend, incl. chain extender and cell-opener | 45 – 62 | 55 |
| water (chemical blowing agent)generates CO2 for expansion | 0.3 – 2.5 | 1.2 |
| silicone surfactantcell regulation | 0.3 – 1.5 | 0.8 |
| amine / tin catalystgel + blow balance | 0.1 – 1 | 0.4 |
| pigment / flame retardant / UV stabilizevariant dependent | 0 – 12 | 2 |
| polymeric MDI / modified MDI (component aromatic isocyanate; aliphatic HDI/IPDI in light-stable grades | ≥ 32 (balance) | — |
PU-Foam-Flexible OPEN — frequently asked
What is PU-Foam-Flexible OPEN used for?
PU-Foam-Flexible OPEN is typically used for cushion/padding prototypes, seating mockups, ergonomic test parts and packaging inserts. In short: softest vacuum-cast foam; high-elongation cushioning grade; integral-skin option available.
What is the tensile strength of PU-Foam-Flexible OPEN?
PU-Foam-Flexible OPEN has a typical tensile strength of 0.25 MPa (0.0363 ksi) — weaker than 100% of polyurethane grades. Strength varies by condition: see the 7 listed tempers.
Is PU-Foam-Flexible OPEN easy to machine?
Not especially — machinability is rated poor (20/100, worse than 95% of polyurethane grades). Trim with sharp blades, hot wire or band knife; milling smears and tears — use very sharp single-flute tools, high rpm, low feed and vacuum support.
Can PU-Foam-Flexible OPEN be welded?
Not readily — weldability is rated not recommended (0/100). Not weldable; join with PU or contact adhesive, or overpour a second shot against the cured foam skin.
What surface finishes work on PU-Foam-Flexible OPEN?
Integral-skin surfaces take flexible PU primer/paint or flock; open-cell foam must be skinned or sealed before painting; sand only with the surface chilled or with abrasive mesh.
Can PU-Foam-Flexible OPEN be formed, bent or molded?
Degas A/B, mix by weight, pour into a silicone vacuum-casting mould with vents and 15–30 % overpack; cream time ~30–60 s, demold 20–60 min, full properties after 24 h (post-cure 60–70 °C accelerates).
What is the maximum service temperature of PU-Foam-Flexible OPEN?
PU-Foam-Flexible OPEN is rated for continuous use to about 70°C (158 °F), and briefly to 100°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Flexible polyurethane foam casting systems (F-series foam resins) — Axson Technologies / Sika Advanced Resins (2021)
- Vacuum casting polyurethane foam and elastomer resins — H&K / Hei-Cast, Smooth-On (2022)
- ISO 1856 Compression set / ISO 3386 Compression stress-strain of flexible cellular materials — ISO (2018)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics (polyurethane foams) — ASM International (1988)
- CES EduPack / Granta eco-property data, flexible PU foam — Ansys Granta (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.